North Korean leader Kim Jong Un has vowed to build up "overwhelming" and unstoppable military power, state media reported Monday, days after he presided over the nation's biggest missile launch.

Kim's comments follow Pyongyang successfully carrying out the launch in defiance of crippling international sanctions on Thursday, the first time the North has fired an intercontinental ballistic missile at full range since 2017.

Known as the Hwasong-17, the powerful ICBM was first unveiled in October 2020 and dubbed a "monster missile" by analysts.

"Only when one is equipped with the formidable striking capabilities, overwhelming military power that cannot be stopped by anyone, one can prevent a war, guarantee the security of the country and contain and put under control all threats and blackmails by the imperialists," Kim told workers involved in the launch, KCNA reported.

North Korean last week fired an ICBM at full range for the first time since 2017
North Korean last week fired an ICBM at full range for the first time since 2017 AFP / Jung Yeon-je

"We will continue to attain the goal of reinforcing national defense capabilities."

The missile launched Thursday -- one of nearly a dozen North Korean weapons tested this year -- appeared to have travelled higher and further than any previous ICBM tested by the nuclear-armed country, including one designed to strike anywhere on the US mainland.

Analysts say the successful launch may have emboldened Kim's confidence that his country is on the right track to achieving nuclear deterrence and that more such tests should be expected.

Long-range and nuclear tests were paused when Kim and then US president Donald Trump engaged in a high-profile bout of diplomacy that subsequently collapsed in 2019. Talks have since stalled.

The launch comes at a delicate time for the region, with South Korea going through a presidential transition until May, and the US distracted by Russia's invasion of Ukraine.